Heat exchanger seal apparatus

ABSTRACT

A heat exchanger includes a heat exchanger shell having an inlet and outlet. A header plate including an inner member and an outer member defining a leak detection chamber therebetween is provided at each end of the heat exchanger shell. A plurality of heat exchanger tubes is positioned in the heat exchanger shell. Each tube extends through an aperture formed in an inner member and an aperture formed in an outer member of each of the header plates. A seal is provided in a channel in each aperture to sealingly engage a corresponding heat exchanger tube and a corresponding plate. A passage leads from the leak detection chamber to the exterior of the header plate.

RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional Application Serial No. 60/236,280, filed Sep. 28, 2000, hereby incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

[0002] The invention relates to heat exchangers, and more particularly, to a heat exchanger with an improved seal apparatus.

BACKGROUND OF THE INVENTION

[0003] Heat exchangers, often referred to as coolers, transfer heat from one fluid to another fluid. For example, in a typical hydraulic system, heat is transferred via a first liquid, such as oil, on the outside of the tubes of a tube bundle to a second cooling liquid, such as water, on the inside of the tubes of the tube bundle. Present designs of heat exchangers, typically used on mobile equipment, have a single tube-to-header plate joint, or seal, on each end of each tube in the tube bundle. The header plate is often referred to as a tube sheet. The joints are designed to prevent leakage or cross-contamination of the fluid on the outside of the tubes to the fluid on the inside of the tubes. The joints may be mechanical, soldered, or welded to provide the tube-to-header plate seal. The joints may alternatively utilize elastomeric seals to provide the tube-to-header plate seal.

[0004] A single tube-to-header plate joint design does not prevent cross contamination of the two heat exchanger fluids if any of the joints fail, and also does not allow for leak detection. One or both working fluids can be routinely examined for evidence that leakage or cross-contamination has occurred, but often the failure of the equipment cooled by the heat exchanger is the first sign that a leak and/or cross-contamination of fluids has occurred. Such a failure is usually very costly.

[0005] Additionally, in conventional heat exchangers that do not use replaceable seals, a repair method often used is to block off the tubes at which a failure has occurred. This leads to a heat exchanger with less cooling than is required.

BRIEF SUMMARY OF THE INVENTION

[0006] The principles of the present invention may be used advantageously to provide heat exchangers with improved sealing capabilities, the capability to detect leaks before cross-contamination of heat exchange fluids occurs, and improved cleaning and repair capabilities.

[0007] In accordance with a first aspect, a heat exchanger includes a heat exchanger shell having an inlet and an outlet, and a pair of header plates. Each header plate is positioned at an end of the heat exchanger shell and includes an outer member and an inner member spaced apart to define a leak detection chamber. A plurality of apertures is provided in each inner member and each outer member, with each aperture having a channel formed therein. Each heat exchanger tube of a plurality of heat exchanger tubes is received by an aperture in the inner member and a corresponding aperture in the outer member of each header plate. Also provided are a plurality of seals, with each seal received in a channel and sealingly engaging a corresponding heat exchanger tube. A passage is provided in each header plate leading from the leak detection chamber to an exterior of the header plate.

[0008] In accordance with a second aspect, a heat exchanger includes a heat exchanger shell having an inlet and an outlet and a pair of header plates. Each header plate is positioned at an end of the heat exchanger shell and includes an inner plate and an outer plate spaced apart to define a leak detection chamber. Each of the inner plates and outer plates has a plurality of apertures, with each aperture having a channel. A passage in each header plate provides fluid communication between the leak detection chamber and an exterior of the heat exchanger. Each heat exchanger tube of a plurality of heat exchanger tubes is received by an aperture in the inner member and a corresponding aperture in the outer member of the header plates at each end of the heat exchanger shell. A seal is received in each channel and sealingly engages the respective channel and a corresponding heat exchanger tube. A cover is secured to each header plate and defines a distribution chamber therebetween, with each end of the heat exchanger tubes extending into one of the distribution chambers. A port in each cover provides fluid communication from the distribution chamber to an exterior of the heat exchanger.

[0009] In accordance with another aspect, a heat exchanger including a pair of header plates. A leak detection chamber is formed in each header plate. Each header plate has a plurality of pairs of apertures. One aperture of each pair of apertures is positioned on one side of the leak detection chamber, and the other aperture of each pair of apertures is positioned on an opposite side of the leak detection chamber. The apertures of each pair of apertures are substantially coaxial, with each aperture having a channel formed therein. Each end of each heat exchanger tube of a plurality of heat exchanger tubes is received by a pair of apertures. Each seal of a plurality of seals is received in a channel and sealingly engages a corresponding heat exchanger tube. A passage in each header plate leads from the leak detection chamber to an exterior of the header plate.

[0010] Other features and advantages of the present invention will become readily apparent to those skilled in the art, given the benefit of this disclosure.

[0011] From this disclosure, it will be readily apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this area of technology, that the present invention provides a significant advance. Preferred embodiments of the heat exchanger seal apparatus of the present invention provide heat exchangers with improved sealing and leak detection capabilities. These and additional features and advantages of the invention disclosed here will be further understood from the following detailed disclosure of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 shows a sectional view of a heat exchanger seal apparatus in accordance with a preferred embodiment of the present invention.

[0013]FIG. 2 shows an enlarged view, partially broken away, of a seal within a channel of the heat exchanger seal apparatus of FIG. 1.

[0014]FIG. 3 shows a sectional view of an alternative embodiment of the seal of FIG. 1.

[0015]FIG. 4 shows a sectional view of another alternative embodiment of the seal of FIG. 1.

[0016]FIG. 5 shows a sectional view of an alternative embodiment of the heat exchanger seal apparatus of FIG. 1.

[0017]FIG. 6 shows a sectional view, partially cut away, of an alternative embodiment of the heat exchanger seal apparatus of FIG. 1.

[0018]FIG. 7 shows a plan view of an alternative embodiment of the leak detection chamber of the heat exchanger seal apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0019] In one preferred embodiment of the present invention, shown in FIG. 1, a heat exchanger 2 includes a heat exchanger shell 4 having a flange 3 at each end thereof. At each end of heat exchanger shell 4, a header plate 6 is secured to flange 3 by bolts (not shown) or other suitable means. A gasket (not shown) is preferably positioned between each flange 3 and header plate 6 to seal the gap therebetween. Heat exchanger shell 4 has a pair of ports 5 to allow the passage of fluid therethrough. Consequently, one port 5 will form an inlet to allow a first fluid to flow into heat exchanger shell 4, while the other port 5 will form an outlet to allow the first fluid to exit heat exchanger shell 4. Each header plate 6 is formed of an outer member, such as outer plate 8 and an inner member, such as inner plate 10. Inner plate 8 and outer plate 10 are spaced apart to define a leak detection chamber 11. A passage 13 extends from chamber 11 outwardly through header plate 16, providing a fluid communication path from chamber 11 to the exterior of heat exchanger 2. In certain preferred embodiments, more than one passage 13 may extend from chamber 11 to the exterior of heat exchanger 2. A plurality of apertures 12 is formed in outer plate 8. A plurality of apertures 15 are formed in inner plate 10, each of which is substantially coaxial with a corresponding aperture 12.

[0020] A plurality of heat exchanger tubes 14 is positioned within heat exchanger shell 4. Each heat exchanger tube 14 is received by and extends through an aperture 15 in the inner plate 10 and an aperture 12 in the outer plate 8 of both header plates 6. A cover or end bonnet 16 having a flange 17 is secured to each header plate 6 by bolts (not shown) or other suitable means, defining a distribution chamber 18 between end bonnet 16 and header plate 6. A gasket (not shown) is typically positioned between each flange 17 and header plate 6 to seal the gap therebetween. A port 19 is provided on each end bonnet 16, providing fluid communication from distribution chamber 18 to the exterior of end bonnet 16. Consequently, one port 19 will form an inlet to allow a second fluid to flow in through an end bonnet 16 and through a corresponding distribution chamber 18 into heat exchanger tubes 14, while the other port 19 will form an outlet to allow the second fluid to exit heat exchanger tubes 14 and a corresponding distribution chamber 18 of the other end bonnet 16.

[0021] The first and second fluids may be any fluid suitable for use in heat exchangers such as, for example, water, oil, glycol solutions, steam, air, or seawater. Other suitable fluids will become readily apparent to those skilled in the art, given the benefit of this disclosure.

[0022] Each aperture 12 in outer plate 8, and each aperture 15 in inner plate 10 is provided with a seal 20 that resiliently engages the exterior surface of a respective heat exchanger tube 14 and the surface of the respective inner plate 10 or outer plate 8, as seen in FIG. 2 with respect to inner plate 10. Thus, each end of each heat exchanger tube 14 has a pair of seals 20 that contact the heat exchanger tube and the heat exchanger 2. Each seal 20 is preferably received in a groove or channel 22. In a preferred embodiment, heat exchanger tubes 14 are cylindrical and channels 22 are annular channels. In the illustrated embodiment, channels 22 have a pair of side walls and a bottom to form a rectangular cross-section. It is to be appreciated that channels 22 may have other cross-sectional shapes. Channels 22 may have any shape suitable for receiving a seal 20 such that the seal may provide sealing engagement between a heat exchanger tube and a respective inner plate 10 or outer plate 8, as well as allowing seal 20 to accommodate thermal expansion and contraction of heat exchanger tubes 14. Channel 22 also advantageously serves to secure the seal 20 within the corresponding plate.

[0023] In certain preferred embodiments, seals 20 are O-rings that seat within channels 22 and resiliently engage the exterior surface of a corresponding heat exchanger tube 14 and channel, providing a seal therebetween. In certain preferred embodiments, seals 20 have a circular cross-section as shown in FIG. 2. In other preferred embodiments, seals 20′ may have a lobed cross-section, as seen in FIG. 3, or, as seen in FIG. 4, seals 20″ may have a rectangular cross-section. Other suitable cross-sections for seals 20 will become readily apparent to those skilled in the art, given the benefit of this disclosure.

[0024] Seals 20 may be formed of an elastomeric material, such as a fluorocarbon-based rubber, ethylene-propylene terpolymer (EPDM), nitrile, or silicon. Seals 20 may be formed of any material suitable for the operating pressures and temperatures and heat exchange fluids found in such heat exchangers, and such suitable materials will become readily apparent to those skilled in the art, given the benefit of this disclosure. In certain preferred embodiments, the seals 20 in inner plate 10 may be formed of a different material than the seals 20 found in outer plate 8, dependent on the fluid to which the seals are exposed.

[0025] Advantageously, if either of the two seals 20 at an end of a heat exchanger tube 14 fails, i.e., the seal in outer plate 8 or the seal in inner plate 10, the other seal prevents the leaking fluid, i.e., either the fluid within heat exchanger tubes 14 or the fluid within shell 4, from contaminating the other fluid. The leaking fluid will flow past the failed seal 20, into chamber 11, and through passage 13 to the exterior of heat exchanger 2, at which point the leak can be detected and can also be collected. When operators or maintenance personnel detect such a leak, they may accordingly take appropriate action including, for example, replacing the faulty seal.

[0026] In a preferred embodiment, a conduit 24 connects passage 13 to a leak detector 26. Conduit 24 may be a pipe, a tube, a hose, or any other suitable device for transferring fluid from passage 13 to leak detector 26. A leak detector may be connected to either or both of the passages 13. Leak detector 26 can also be connected to one or more passages of one or more other heat exchangers. Leak detector 26 preferably provides an indicator via a signal to indicate to alert an individual that a leak has occurred. The signal may be an audible signal, for example, that produced by a speaker 28. Other devices producing audible signals are considered to be within the scope of the invention including, for example, buzzers, bells and sirens. Alternatively, the signal could be a visual signal produced by a light 30. Other devices producing visual signals are considered to be within the scope of the invention including, for example, a message displayed on a computer monitor. Alternatively, leak detector 26 could send a signal by, for example, a cable or wire 32, to a valve 34 to shut off flow of the leaking fluid. Suitable leak detectors include, for example, capacitance switches, inductance switches, float switches, pressure transducers, fluid level indicators, and fluid type indicators. Other suitable leak detectors are well known to those skilled in the art, and further description will not be provided here.

[0027] The use of a pair of replaceable seals at each end of the heat exchanger tubes, particularly elastomeric seals, provides numerous advantages. First, the pair of seals and the corresponding leak detection chamber and passage provides the ability for early leak detection, before cross-contamination of the heat exchange fluids occurs. Secondly, elastomeric seals absorb thermal expansion and contraction stresses normally found in heat exchangers, reducing the stresses incurred by the heat exchanger itself. Additionally, since the seals are removable, the heat exchanger can be completely disassembled and thoroughly cleaned. Further, any damaged seals can be easily replaced, resulting in a heat exchanger in like-new condition.

[0028] It is to be appreciated that baffles (not shown) may be disposed within heat exchanger shell 4, in order to redirect the flow of the second fluid over and around the heat exchanger tubes 14, thereby increasing the heat transfer within the heat exchanger.

[0029] Another preferred embodiment is shown in FIG. 5, in which heat exchanger 2 has no shell enclosing heat exchanger tubes 14. In this embodiment, heat exchanger tubes 14 may be exposed to, for example, ambient air. Support members 36 having flanges 38 may extend between and be secured to header plates 6, thereby providing structural support for heat exchanger 2 between the header plates 6.

[0030] Another preferred embodiment is shown in FIG. 6, where outer plate 8′ and inner plate 10′ of header plate 6′ are separated by a spacer 40. Gaskets (not shown) are preferably positioned between outer plate 8′ and spacer 40, and between inner plate 10′ and spacer 40. Passage 13 extends through spacer 40, connecting leak detection chamber 11 with the exterior of the heat exchanger.

[0031] It is to be appreciated that leak detection chamber 11 can be formed in many different ways. In one preferred embodiment, leak detection chamber 11 could be machined into a surface of outer plate 8 or inner plate 10. The plates can then be sandwiched together such that the leak detection chamber extends between the two plates. Alternatively, mirror images of leak detection chamber could be machined into both outer plate 9 and inner plate 10, with each portion defining half of the chamber such that when the plates are sandwiched together, the full leak detection chamber is defined by and extends between the plates.

[0032] Another embodiment is shown in FIG. 7, in which a plurality of elliptical chambers 42 is formed in header plate 6, for example, by machining. Each chamber 42 extends between each aperture of a pair of coaxial apertures 12, 15 in outer plate 8 and inner plate 10, respectively. The chambers 42 adjacent to one another within a row of apertures overlap one another to define openings 44, thereby interconnecting all of the chambers 42 in a given row. Interconnecting passages 46 extend between selected chambers 42 of adjacent rows of apertures. Therefore, the combination of chambers 42, openings 44 and passages 46 defines leak detection chamber 11′.

[0033] While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims. 

We claim:
 1. A heat exchanger comprising, in combination: a heat exchanger shell having an inlet and an outlet; a pair of header plates, each header plate positioned at an end of the heat exchanger shell and including an outer member and an inner member spaced apart to define a leak detection chamber; a plurality of apertures in each inner member and outer member, each aperture having a channel formed therein; a plurality of heat exchanger tubes, each heat exchanger tube received by an aperture in the inner member and a corresponding aperture in the outer member of each header plate; a plurality of seals, each seal received in a channel and sealingly engaging a corresponding heat exchanger tube; and a passage in each header plate leading from the leak detection chamber to an exterior of the header plate.
 2. The heat exchanger of claim 1, wherein the outer member comprises a plate.
 3. The heat exchanger of claim 1, wherein the inner member comprises a plate.
 4. The heat exchanger of claim 1, wherein the seals are O-rings.
 5. The heat exchanger of claim 1, wherein the seals have a lobed cross-section.
 6. The heat exchanger of claim 1, wherein the seals have a rectangular cross-section.
 7. The heat exchanger of claim 1, wherein the seals are formed of an elastomeric material.
 8. The heat exchanger of claim 1, further comprising a leak detector and a conduit connecting the leak detector to the passage.
 9. The heat exchanger of claim 8, wherein the leak detector includes a visual signal indicator providing a signal indicating that a leak has been detected.
 10. The heat exchanger of claim 8, wherein the leak detector includes an audible signal indicator providing a signal indicating that a leak has been detected.
 11. The heat exchanger of claim 8, wherein the leak detector includes a valve configured to stop a flow of a heat exchange fluid upon detection of a leak.
 12. The heat exchanger of claim 1, wherein the heat exchanger tubes have a cylindrical profile.
 13. The heat exchanger of claim 1, wherein the channels are formed of a pair of side walls and a bottom.
 14. The heat exchanger of claim 1, further comprising a cover secured to each header plate and defining a distribution chamber therebetween, one cover having an inlet port and the other cover having an outlet port.
 15. A heat exchanger comprising, in combination: a heat exchanger shell having an inlet and an outlet; a pair of header plates, each header plate being positioned at an end of the heat exchanger shell and including an inner plate and an outer plate spaced apart to define a leak detection chamber, each of the inner plates and outer plates having a plurality of apertures extending therethrough, each aperture having a channel; a passage in each header plate providing fluid communication between the leak detection chamber and an exterior of the heat exchanger; a plurality of heat exchanger tubes, each heat exchanger tube being received by an aperture in the inner member and a corresponding aperture in the outer member of the header plates at each end of the heat exchanger shell; a plurality of seals, each seal received by a channel and sealingly engaging the respective channel and a corresponding heat exchanger tube; a cover secured to each header plate and defining a distribution chamber therebetween, each end of the heat exchanger tubes extending into one of the distribution chambers; and a port in each cover to provide fluid communication from the distribution chamber to an exterior of the heat exchanger.
 16. The heat exchanger of claim 15, further comprising a leak detector connected to the passage by a conduit.
 17. The heat exchanger of claim 15, wherein the seals are O-rings.
 18. The heat exchanger of claim 15, wherein the seals have a lobed cross-section.
 19. The heat exchanger of claim 15, wherein the seals have a rectangular cross-section.
 20. The heat exchanger of claim 15, wherein the seals are formed of an elastomeric material.
 21. A heat exchanger comprising, in combination: a pair of header plates; a leak detection chamber formed in each header plate; a plurality of pairs of apertures in each header plate, one aperture of each pair of apertures being positioned on one side of the leak detection chamber, the other aperture of each pair of apertures being positioned on an opposite side of the leak detection chamber, the apertures of each pair of aperture being substantially coaxial, with each aperture having a channel formed therein; a plurality of heat exchanger tubes, each end of each heat exchanger tube received by a pair of apertures; a plurality of seals, each seal received in a channel and sealingly engaging a corresponding heat exchanger tube; and a passage in each header plate leading from the leak detection chamber to an exterior of the header plate. 